Synthesis, Coated And Electrochemical Properties Of ASP Cathode Materials For Lithium Ion Batteries

The current lithium ion battery cathode material LiCoO2is still dominant.Due to its high toxicity, poor safety and high cost, researchers are looking fornew cathode materials which can substitute for LiCoO2. While ternarycomposite LiNi1/3Co1/3Mn1/3O2have similar structure to LiCoO2, and itsadvantage of high safety, high reversible capacity and low cost, it couldbecome a viable alternative to LiCoO2. This article is reviews usingcoprecipitation synthetise LiNi1/3Co1/3Mn1/3O2material under the optimumconditions, and carries on the coated modification research.With hydroxyl coprecipitation synthetise LiNi1/3Co1/3Mn1/3O2material,the optimal precursor synthesis process was pH=11.0, the concentration ofammonia1.0mol L-1. The optimal calcination method was Li/M=1.05,calcination at900℃for15h after precalcination at500℃for5h and at200℃for3h in air. The initial discharge capacity of the as-preparedLiNi1/3Co1/3Mn1/3O2was183mAh g-1at a current density of20mA g-1overthe voltage range of2.5~4.5V and the capacity retention was88.9%after40cycles. Y2O3was coated on the surface of LiNi1/3Co1/3Mn1/3O2to improve itscirculation features, and by means of SEM, XRD, charge and discharge test toexamine the different amount of cladding on LiNi1/3Co1/3Mn1/3O2the influenceof the structure and electrochemical performance. The results show that thecoating has not changed the structure of LiNi1/3Co1/3Mn1/3O2; and the bestamount of Y2O3coated was located at0.5wt%. With the increase of amount ofcladding, LiNi1/3Co1/3Mn1/3O2first discharge capacity reduce gradually. Theinitial discharge capacity of the0.5wt%of Y2O3coated LiNi1/3Co1/3Mn1/3O2was196.4mAh g-1at a current density of20mA g-1over the voltage rangeof2.5~4.5V and the capacity retention was99.3%after40cycles.Using commercialized anode materials LiNi0.5Co0.2Mn0.3O2as rawmaterial and adopting coprecipitation to study by cladding it with Y2O3, YPO4,Al2O3, AlPO4respectively. The XRD result shows that after coating the fourphosphates of0.5wt%, LiNi0.5Co0.2Mn0.3O2has a better layered structure and alower extent of nickel lithium mixed than before. After50cycles at0.1C ratiocycle, the discharge capacity were190.5mAh/g,185.9mAh/g,191.3mAh/g,196.1mAh/g, which all higher than not coated material of173.5mAh/g, and the capacity retention were98.9%,95.0%,99.1%,95.0%, those weresignificantly higher than the92.3%without cladding material.The spherical LiNi0.8Co0.15Al0.05O2cathode material for lithium ionbattery was prepared by coprecipitation-spray drying method. The effectsof oxygen flow rate，calcination method, temperature and time andLi/M ratios on the performance of LiNi0.8Co0.15Al0.05O2werestudied by X-ray diffraction (XRD), scanning electronmicroscope(SEM) and charge-discharge testsThermogravimetric(TG), X-raydiffraction(XRD), scanning electron microscopy(SEM) and electrochemicaltests were used to characterize the structure, appearance and electrochemicalperformance of LiNi0.8Co0.15Al0.05O2. The material had optimal layeredstructure, the spherical particle size was uniformly distributed in10μm. Whencycled in2.5-4.3V at30℃, the20mA/g initial specific discharge capacitywas186.3mAh/g, the capacity retention was84.1%at the50thcycle.